Chamber pressure

About: Chamber pressure is a research topic. Over the lifetime, 2988 publications have been published within this topic receiving 30725 citations.

Initial Growth Rate and Visual Characteristics of a Round Jet into a Sub- to Supercritical Environment of Relevance to Rocket, Gas Turbine, and Diesel Engines

Abstract: : The combustion chamber temperature and pressure in many liquid rocket, gas turbine, and diesel engines are quite high and can reach levels above the critical point for the injected fuels and/or oxidizers. A high pressure chamber is used to investigate and understand the nature of the interaction between the injected fluid and the environment under such conditions. Pure N2 He, and O2 fluids are injected. Several chamber media are selected including, N2, He, and mixtures of CO+N2. The effects of chamber pressure ranging from a subcritical (i.e. relative pressure, P(sub r) = P/P (sub injectant critical 1) value at a supercritical chamber temperature (relative temperature T sub r = T/T sub injectant critical >1) are photographically observed and documented near the injector hole exit region using a CCD camera illuminated by a short-duration back-lit strobe light. At low subcritical chamber pressures, the jets exhibit surface irregularities that amplify downstream, looking intact, shiny, but wavy (sinuous) on the surface that eventually break up into irregularly-shaped small entities.

Haptic jamming: A deformable geometry, variable stiffness tactile display using pneumatics and particle jamming

Abstract: Many controllable tactile displays present the user with either variable mechanical properties or adjustable surface geometries, but controlling both simultaneously is challenging due to electromechanical complexity and the size/weight constraints of haptic applications. This paper discusses the design, manufacturing, control, and preliminary evaluation of a novel haptic display that achieves both variable stiffness and deformable geometry via air pressure and a technique called particle jamming. The surface of the device consists of a flat, deformable layer of hollow silicone cells filled with coffee grounds. It selectively solidifies in different regions when the air is vacuumed out of individual cells, jamming the coffee particles together. The silicone layer is clamped over a chamber with regulated air pressure. Different sequences of air pressure and vacuum level adjustment allow regions of the surface to display a small rigid lump, a large soft plane, and various other combinations of lump size and stiffness. Experimental data from individual cells show that surface stiffness increases with vacuum level and the elliptical shape of the cells become increasingly spherical with increased chamber pressure.

Method and apparatus for determining the endpoint in a plasma cleaning process

Abstract: Apparatus and methods are disclosed for utilizing a plasma cleaning operation of a CVD system incorporating cleaning process endpoint detection. In one embodiment, the cleaning process is performed at a constant exhaust capacity and the endpoint detection is in response to a specified rate of change of chamber pressure. In another embodiment, a servo-controlled exhaust system maintains a controlled chamber pressure and the endpoint detection is in response to a specified control signal. In a preferred embodiment, nitrogen trifluoride is converted into a plasma containing free fluorine radicals in a magnetron-powered remote microwave plasma generator. The remotely produced free fluorine radicals are used to remove silicon nitride deposits from a substrate processing chamber. The use of such a remote plasma system provides an efficient cleaning process that takes as little as half the time compared to similar in situ plasma cleaning processes. The incorporation of endpoint detection provides optimal cleaning time for the remote plasma cleaning process.

Combustion Experiments in Hydrogen Peroxide/Polyethylene Hybrid Rocket with Catalytic Ignition

Abstract: Resultsfrom 100 tests oflab-scalehybrid rocketmotorsusing hydrogen peroxideand polyethylenearepresented herein. The bulk of the tests utilized 85% hydrogen peroxide with low-density polyethylene. A new consumable catalytic-ignition device has been developed to provide rapid, reliable ignition using stabilized hydrogen peroxide. Regression measurements indicate that at low chamber pressures (100psi)a classic diffusion-dominated behavior is noted with mass e ux exponents very near the theoretical value of 0.8. However, at higher chamber pressures tested (200 and 400 psi ),radiative-dominated behaviorisnoted foraveragemasse uxes varying between 0.1 and 0.3 lbm/(in. 2 s). Through the optimization of aft mixing length, combustion efe ciencies in excess of 95% were obtained in these tests. No signie cant nonacoustic or acoustic instabilities were noted in these tests; chamber pressure e uctuations were less than 3.5% zero-to-peak of mean.